<!DOCTYPE HTML>
<html xmlns="http://www.w3.org/1999/xhtml">

<head>
  <title>Test Index</title>
</head>

<body class="bootstrap index-page">
  <style>
    .elem-a {
      width: 14px;
      height: 18px;
    }

    .group {
      margin-top: 50px;
      margin-left: 40px;
      width: 14px;
      height: 18px;
    }

    .elem-b {
      display: none;
    }

    .group:hover .elem-b {
      display: block;
    }
  </style>
  <div class="elem-a">
    A
  </div>
  <div class="group">
    <div class="elem-b">B</div>
  </div>
</body>

</html>